More than a third of the injuries happen while bathing or showering. More than 14 percent occur while using the toilet.

Injuries increase with age, peaking after 85, the researchers found. But injuries around the tub or shower are proportionately most common among those ages 15 to 24 and least common among those over 85. People over 85 suffer more than half of their injuries near the toilet.

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Fainting is not a common cause of injury, but it occurred most often in the 15-to-24 age group. Alcohol use may be a factor, the researchers suggested, but there is no data to prove it.

The bathroom injury rate for women was 72 percent higher than for men, the analysis found. Studies have shown that women are at higher risk than men for injuries in falls, and the authors speculate that the disparity might also be attributed to differences in physical activity, lower-body strength, bone mass or even more willingness to seek treatment.

The most hazardous activities for all ages are bathing, showering and getting out of the tub or shower. (Only 2.2 percent of injuries occur while getting into the tub or shower, but 9.8 percent occur while getting out.) Injuries in or near the bathtub or shower account for more than two-thirds of emergency room visits.

“Injuries getting on and off the toilet are quite high in people 65 and older,” said Judy A. Stevens, an epidemiologist with the C.D.C. and the lead author of the report. “Having grab bars by the toilet would be helpful for people in their older years, and everyone would benefit from having grab bars both inside the tub or shower and where you get in and out.”

The analysis appeared in the June 10 issue of the Morbidity and Mortality Weekly Report. NICHOLAS BAKALAR

A version of this article appears in print on August 16, 2011, on Page D7 of the New York edition with the headline: Watch Your Step While Washing Up. Order Reprints|Today's Paper|Subscribe